TWI740619B - Control circuit and control method for power converter - Google Patents

Abstract

A control circuit and a control method for a power converter are provided. The power converter includes a plurality of resonant tanks and a plurality of switches disposed between an input end and an output end, the switches correspond to a first mode and a second mode, respectively, and the control circuit includes a first switch control circuit, a first zero current detection circuit, a second zero current detection circuit, a first switch off detector, a modulation time calculation module, a second switch control circuit, a third zero current detection circuit, a fourth zero current detection circuit, and a second switch off detector. The control circuit uses a plurality of zero current detection circuits to perform time modulations on a plurality of rectifier switches in the switches.

Description

Control circuit and control method for power converter

The invention relates to a control circuit and a control method, in particular to a control circuit and a control method for a power converter.

In the existing switching resonant tank converter circuit, it is only proposed to automatically adjust the on-time to individually control the off timing of the rectifier switch to achieve the optimization of efficiency. However, in parallel applications, no solution is proposed for the current sharing of multiple sets of converters.

Therefore, how to improve the control mechanism to retain the old automatic adjustment of the on-time control, so that the overall converter can be optimized in terms of efficiency, and at the same time, the output voltage and output impedance can be adjusted, and the parallel output can be balanced. The function of streaming to overcome the above-mentioned shortcomings has become one of the important issues to be solved by this business.

The technical problem to be solved by the present invention is to provide a control circuit and control method for a power converter in view of the shortcomings of the prior art.

In order to solve the above technical problems, one of the technical solutions adopted by the present invention is to provide a control method for a power converter, wherein the power converter includes a plurality of resonance tanks arranged between an input terminal and an output terminal And a plurality of switches, wherein the open relations respectively correspond to a first mode and a second mode, and the input terminal receives an input voltage, the control method includes: configuring a first switch control circuit in the first mode Next, controlling the conduction of a plurality of switches corresponding to the first mode to respectively form a first resonant current along a first resonant path and a second resonant current along a second resonant path through the resonant slots, The switches include a first rectifier switch located on the first resonant path and a second rectifier switch located on the second resonant path; a first zero current detection circuit is configured to detect the first rectifier The first resonant current on the switch outputs a first current zero signal when it is detected that the first resonant current reaches the current zero point so that the first switch control circuit controls the first rectifier switch to turn off; configure a second The zero current detection circuit detects the second resonant current on the second rectifier switch, and when it is detected that the second resonant current reaches the current zero point, it outputs a second current zero point signal so that the first switch control circuit controls the The second rectifier switch is turned off; a first switch off detector is configured to detect whether the first rectifier switch and the second rectifier switch are both turned off, and the first rectifier switch and the second rectifier switch are both turned off When off, output a first modulation time calculation signal; configure a modulation time calculation module, in response to receiving the first modulation time calculation signal, calculate a first modulation based on a feedback voltage from the output terminal Time, and after the first rectifier switch and the second rectifier switch are turned off, a second mode activation signal is output after the first modulation time has elapsed; a second switch control circuit is configured to respond to receiving the second The mode activation signal controls the conduction of the switches corresponding to the second mode to respectively form a third resonance current along a third resonance path and a fourth resonance along a fourth resonance path through the resonance tanks Current, wherein the switches include a third rectifier switch located on the third resonance path and a fourth rectifier switch located on the fourth resonance path; a third zero current detection circuit is configured to detect the first The third resonant current on the three rectifier switch outputs a third current zero point signal when it is detected that the third resonant current reaches the current zero point so that the second switch control circuit controls the first rectifier switch to turn off; configuration one The fourth zero current detection circuit detects the fourth resonant current on the fourth rectifier switch, and when it is detected that the second resonant current reaches the current zero point, it outputs a fourth current zero point signal to enable the second switch control circuit Control the fourth rectifier switch to turn off; configure a second switch turn-off detector to detect whether the third rectifier switch and the fourth rectifier switch are both turned off, and switch between the third rectifier switch and the fourth rectifier switch When both are turned off, output a second modulation time calculation signal; and configure the modulation time calculation module to respond to receiving the second modulation time calculation signal according to The feedback voltage calculates a second modulation time, and after the third rectifier switch and the fourth rectifier switch are turned off, and after the second modulation time has elapsed, a first mode activation signal is output.

In some embodiments, the control method for the power converter further includes configuring the first switch control circuit, and in response to receiving the first modulation time calculation signal, controlling the switches corresponding to the first mode, the The switches other than the first rectifier switch and the second rectifier switch are turned off during the first modulation time after the first rectifier switch and the second rectifier switch are turned off.

In some embodiments, the control method for the power converter further includes configuring the second switch control circuit, in response to receiving the second modulation time calculation signal, controlling the switches corresponding to the second mode, the The switches other than the third rectifier switch and the fourth rectifier switch are turned off during the second modulation time after the third rectifier switch and the fourth rectifier switch are turned off.

In some embodiments, the modulation time calculation module includes a first calculation unit and a second calculation unit, and the control method further includes: configuring the first calculation unit, in response to receiving the first modulation time calculation Signal, calculate the first modulation time according to the feedback voltage, and output the second mode start signal after the modulation time has elapsed after the first rectifier switch and the second rectifier switch are turned off; and configure the The second calculation unit, in response to receiving the second modulation time calculation signal, calculates the second modulation time according to the feedback voltage, and after the third rectifier switch and the fourth rectifier switch are turned off, The first mode activation signal is output after the second modulation time.

In some embodiments, the modulation time calculation module includes a third calculation unit and a phase shifter, and the control method further includes: configuring the third calculation unit in response to receiving the first modulation time calculation signal Or when calculating the signal for the second modulation time, calculate a total modulation time according to the feedback voltage and generate a time modulation signal correspondingly; configure the phase shifter to respond to receiving the modulation time signal according to the One half of the total modulation time phase shifts the modulation time signal to generate a phase-shifted modulation time signal, and uses the modulation time signal and the phase-shifted modulation time signal as the second mode respectively The activation signal and the first mode activation signal.

In order to solve the above technical problem, another technical solution adopted by the present invention is to provide a control circuit for a power converter, wherein the power converter includes a plurality of resonance tanks arranged between an input terminal and an output terminal. And a plurality of switches, wherein the open relations respectively correspond to a first mode and a second mode, and the input terminal receives an input voltage. The control circuit includes a first switch control circuit, a first zero current detection circuit, The twentieth current detection circuit, the first switch off detector, the modulation time calculation module, the second switch control circuit, the third zero current detection circuit, the fourth zero current detection circuit, and the second switch off Detector. The first switch control circuit is configured to control the conduction of a plurality of switches corresponding to the first mode in the first mode, so as to respectively form a first resonant current along a first resonant path and along a first resonant path through the resonant tanks. A second resonant current along a second resonant path, wherein the switches include a first rectifier switch located on the first resonant path and a second rectifier switch located on the second resonant path. The first zero current detection circuit is configured to detect the first resonant current on the first rectifier switch, and when it is detected that the first resonant current reaches the current zero point, it outputs a first current zero point signal so that the first The switch control circuit controls the first rectifier switch to turn off. The twentieth current detection circuit is configured to detect the second resonant current on the second rectifier switch, and when detecting that the second resonant current reaches the current zero point, it outputs a second current zero point signal so that the first The switch control circuit controls the second rectifier switch to turn off. The first switch turn-off detector is configured to detect whether the first rectifier switch and the second rectifier switch are both turned off, and when the first rectifier switch and the second rectifier switch are both turned off, output a first 1. Calculate the signal for modulation time. The modulation time calculation module is configured to, in response to receiving the first modulation time calculation signal, calculate a first modulation time based on a feedback voltage from the output terminal, and set the first rectifier switch and the first rectifier switch to After the two rectifier switches are turned off, a second mode start signal is output after the first modulation time has elapsed. The second switch control circuit is configured to control the switches corresponding to the second mode to be turned on in response to receiving the second mode activation signal, so as to form a first along a third resonance path through the resonant tanks. Three resonant currents and a fourth resonant current along a fourth resonant path, wherein the switches include a third rectifier switch located on the third resonant path and a fourth resonant switch located on the fourth resonant path Rectifier switch. The third zero current detection circuit is configured to detect the third resonant current on the third rectifier switch, and when it is detected that the third resonant current reaches the current zero point, it outputs a third current zero point signal so that the first The second switch control circuit controls the first rectifier switch to turn off. The fourth zero current detection circuit is configured to detect the fourth resonant current on the fourth rectifier switch, and when it is detected that the second resonant current reaches the current zero point, it outputs a fourth current zero point signal to enable the first The second switch control circuit controls the fourth rectifier switch to turn off. The second switch turn-off detector is configured to detect whether the third rectifier switch and the fourth rectifier switch are both turned off, and when the third rectifier switch and the fourth rectifier switch are both turned off, output a The second modulation time calculation signal. Wherein, the modulation time calculation module is further configured to, in response to receiving the second modulation time calculation signal, calculate a second modulation time based on the feedback voltage, and perform the operation between the third rectifier switch and the fourth rectifier After the switch is turned off, and after the second modulation time has elapsed, a first mode activation signal is output.

One of the beneficial effects of the present invention is that the control circuit and control method for a power converter provided by the present invention can enable the rectifier switch of a power converter with multiple sets of rectification paths through a zero current detection circuit. Determine the on-time individually. Not only can it overcome the different conduction time of the rectifier switch caused by the component error of the individual rectifier loop, but also can achieve the function of zero voltage turn-on and zero current cut-off of the rectifier component, so as to optimize the overall efficiency of the power converter.

In addition, after ensuring that all rectification paths of the power converter have completed zero current cutoff, adjust the trigger timing of the switching signal of the power converter to achieve the modulation of the converter output impedance, achieve the output adjustable voltage, and the parallel output can share the current function. .

In order to further understand the features and technical content of the present invention, please refer to the following detailed description and drawings about the present invention. However, the provided drawings are only for reference and description, and are not used to limit the present invention.

The following is a specific embodiment to illustrate the implementation of the “control circuit and control method for power converter” disclosed in the present invention. Those skilled in the art can understand the advantages and effects of the present invention from the content disclosed in this specification. . The present invention can be implemented or applied through other different specific embodiments, and various details in this specification can also be based on different viewpoints and applications, and various modifications and changes can be made without departing from the concept of the present invention. In addition, the drawings of the present invention are merely schematic illustrations, and are not drawn according to actual dimensions, and are stated in advance. The following embodiments will further describe the related technical content of the present invention in detail, but the disclosed content is not intended to limit the protection scope of the present invention. In addition, the term "or" used in this document may include any one or a combination of more of the associated listed items depending on the actual situation.

[First Embodiment]

Fig. 1 is a functional block diagram of a control circuit for a power converter according to a first embodiment of the present invention. Referring to FIG. 1, the first embodiment of the present invention provides a control circuit for a power converter, in which further reference can be made to FIG. 2, which is a circuit layout diagram of the power converter according to the first embodiment of the present invention. As shown in FIG. 2, the power converter can be a switched tank converter (Switched Tank Converter, STC), which includes resonant tanks RS1, RS2 and switches Q1 to Vout provided between an input terminal Vin and an output terminal Vout. Q12, where the switches Q1 to Q12 can respectively correspond to the first mode Φ1 and the second mode Φ2, and the input terminal Vin receives an input voltage. The resonant tank RS1 may include a resonant capacitor CR1 and a resonant inductor LR1. The resonant tank RS2 may include a resonant capacitor CR2 and a resonant inductor LR2. The non-resonant capacitor CF1 is separated from the resonant tanks RS1 and RS2 and does not contribute to the characteristics of the resonant tanks RS1 and RS2. Capacitance at the resonant frequency. In this embodiment, only one non-resonant capacitor CF1 is included in the circuit. However, depending on the topology of the STC circuit, more than one non-resonant capacitor may be used. In a specific switching state, depending on the circuit topology and application, each resonant tank RS1, RS2 can be connected in series or in parallel with a specific non-resonant capacitor.

Each of the plurality of switches Q1 to Q12 has a first terminal, a second terminal, a control terminal, and a corresponding body diode. The control terminal can receive a control signal to make the switch in an off state or an on state. In the embodiment of Figure 1, N-channel MOSFET switches are used. However, other types of switches can also be used. Among the switches Q1 to Q12, the switches Q1, Q4, Q5, Q7, Q10, and Q11 correspond to the first mode Φ1, the switches Q2, Q3, Q6, Q8, Q9, and Q12 correspond to the second mode Φ2, and in the first mode In Φ1 and the second mode Φ2, the off state or on state of the switches Q1 to Q12 are mutually exclusive.

The control circuit 1 of the present invention is further described. As shown in Figure 1, the control circuit 1 includes a first switch control circuit SW1, a first zero current detection circuit ZCD1, a second zero current detection circuit ZCD2, a first switch off detector OFFC1, a modulation time calculation module Group TMC, the second switch control circuit SW2, the third zero current detection circuit ZCD3, the fourth zero current detection circuit ZCD4, and the second switch off detector OFFC2.

The details of each part of the control circuit 1 will be described below based on FIG. 3. Please refer to FIG. 3, which is a switch timing diagram according to the first embodiment of the present invention.

As shown in FIG. 3, the first mode Φ1 starts from time t0, and the first switch control circuit SW1 is configured to control the plurality of switches corresponding to the first mode Φ1 to be turned on in the first mode Φ1. For example, the switches Q1, Q4, Q5, Q7, Q10, and Q11 are controlled by the switching signals VGS1, VGS4, VGS5, VGS7, VGS10, and VGS11, respectively, and correspond to the switches Q2, Q3, Q6, Q8, and Q8 of the second mode Φ2. Q9 and Q12 are controlled by switching signals VGS2, VGS3, VGS6, VGS8, VGS9 and VGS12. In this case, the first resonant current i1 along the first resonant path L1 and the second resonant current i2 along the second resonant path L2 can be formed by the resonant slots RS1 and RS2, respectively.

The switches Q1, Q4, Q5, Q7, Q10, and Q11 include a first rectifier switch located on the first resonance path L1, and a second rectifier switch located on the second resonance path L2. For example, it can be seen from the figure that the body diodes of the switches Q11 and Q7 follow the direction of the current, and therefore have a rectifying function, which can be used as the aforementioned first rectifier switch and second rectifier switch, respectively. In the first resonance path L1, the switch Q10 can also be used as the first rectifier switch, but the switch Q11 is used in this embodiment.

Then, the first zero current detection circuit ZCD1 is configured to detect the first resonant current i1 on the first rectifier switch (the switch Q11 at this time), in other words, to detect the switch current ISD11 on the switch Q11, when the detection When the first resonant current i1 (ie, the switch current ISD11) is measured to reach the current zero point, the first current zero point signal is output so that the first switch control circuit SW1 controls the first rectifier switch (switch Q11) to turn off. This time is time t1 .

At the same time, when the second resonant path L2 is generated, the second zero current detection circuit ZCD2 is also configured to detect the second resonant current i2 on the second rectifier switch (in this case, the switch Q7), in other words, to the switch The switch current ISD7 on Q7 is detected. When the second resonant current i2 reaches the current zero point, the second current zero point signal is output so that the first switch control circuit SW1 controls the second rectifier switch (switch Q7) to turn off. This is time t2.

The reason for using the first zero current detection circuit ZCD1 and the second zero current detection circuit ZCD2 for detection is that the resonance tanks RS1 and RS2 of the power converter may not match each other, resulting in different resonance frequencies. Therefore, in order to make the first A resonant path L1 and a second resonant path L2 can each operate at the resonant frequency. The first zero current detection circuit ZCD1 and the second zero current detection circuit ZCD2 are configured to detect the turn-on time of the switches Q11 and Q7 and control them. The first switch control circuit SW1 will be the most efficient method.

Further, the first switch off detector OFFC1 is configured to detect whether the first rectifier switch and the second rectifier switch are both off. At time t2, when it is detected that both the first rectifier switch (switch Q11) and the second rectifier switch (switch Q7) are turned off, the first modulation time calculation signal is output.

Then, the modulation time calculation module TMC is configured to calculate the first modulation time MT1 according to the feedback voltage from the output terminal Vout in response to receiving the first modulation time calculation signal. For example, the output terminal Vout can be connected to a feedback circuit FB to transmit the feedback voltage of the output terminal Vout to the modulation time calculation module TMC. If the output voltage is too high, the longer first modulation will be calculated. The time MT1 is changed to decrease the output voltage, and if the output voltage is too low, a shorter first modulation time MT1 is calculated to increase the output voltage. In this embodiment, the feedback voltage can be compared with a predetermined voltage, and the error between the two can be converted into the length of the first modulation time MT1 after passing through the compensator. In the first modulation time MT1, the first rectifier switch (switch Q11) and the second rectifier switch (switch Q7) are both in the off state.

For the switches Q1, Q4, Q5, Q7, Q10, and Q11 corresponding to the first mode Φ1, the switches Q1, Q4, Q5, Q10 other than the first rectifier switch (switch Q11) and the second rectifier switch (switch Q7) In other words, the first switch control circuit SW1 can be controlled by a fixed control method. The first switch control circuit SW1 can be configured to control the switches Q1, Q4, Q5, and Q10 to turn off the first rectifier switch (switch Q11) and the second rectifier switch (switch Q7) in response to receiving the first modulation time calculation signal. Turn off in the first modulation time MT1 after turning off.

In addition, after the first rectifier switch (switch Q11) and the second rectifier switch (switch Q7) are turned off, and after the first modulation time MT, the modulation time calculation module TMC can output the second mode start signal. Time is time t3.

At time t3, the second switch control circuit SW2 is configured to control the switches Q2, Q3, Q6, Q8, Q9, and Q12 corresponding to the second mode Φ2 to turn on in response to receiving the second mode activation signal to pass resonance The slots RS1 and RS2 respectively form a third resonance current i3 along the third resonance path L3 and a fourth resonance current i4 along the fourth resonance path L4. Similarly, the switches Q2, Q3, Q6, Q8, Q9, and Q12 include a third rectifier switch (in this case, switch Q9) located on the third resonant path L3 and a fourth rectifier switch located on the fourth resonant path L4 (At this time, switch Q12).

Then, the third zero current detection circuit ZCD3 is configured to detect the third resonant current i3 on the third rectifier switch (switch Q9), in other words, detect the switch current ISD9 on the switch Q9, when the first When the three-resonant current (that is, the switching current ISD9) reaches the current zero point, the third current zero point signal is output so that the second switch control circuit SW2 controls the third rectifier switch (switch Q9) to turn off. At this time, it is time t4.

At the same time, when the fourth resonant path L4 is generated, the fourth zero current detection circuit ZCD4 is configured to detect the fourth resonant current i4 (that is, the switch current ISD12) on the fourth rectifier switch (switch Q12). When the fourth resonant current i4 (switch current ISD12) is detected to reach the current zero point, a fourth current zero point signal is output so that the second switch control circuit SW2 controls the fourth rectifier switch (switch Q12) to turn off, which is time t5. Similarly, configuring the third zero current detection circuit ZCD3 and the fourth zero current detection circuit ZCD4 to detect the on-times of the switches Q9 and Q12 individually required to control the second switch control circuit SW2 will be the most efficient method.

Furthermore, the second switch off detector OFFC2 is configured to detect whether the third rectifier switch and the fourth rectifier switch are both off. And when the third rectifier switch and the fourth rectifier switch are both turned off, a second modulation time calculation signal is output. Wherein, at time t5, when it is detected that both the third rectifier switch (switch Q9) and the fourth rectifier switch (switch Q12) are turned off, the first modulation time calculation signal is output.

Then, the modulation time calculation module TMC is further configured to calculate the second modulation time MT2 according to the feedback voltage from the output terminal Vout in response to receiving the second modulation time calculation signal. For example, the output terminal Vout can be connected to the feedback circuit FB to transmit the feedback voltage of the output terminal Vout to the modulation time calculation module TMC. If the output voltage is too high, a longer second modulation will be calculated The time MT2 is used to decrease the output voltage, and if the output voltage is too low, a shorter second modulation time MT2 is calculated to increase the output voltage. In this embodiment, the feedback voltage can be compared with a predetermined voltage, and the error between the two can be converted into the time length of the second modulation time MT2 after passing through the compensator. In the second modulation time MT2, the third rectifier switch (switch Q9) and the fourth rectifier switch (switch Q12) are both in an off state.

In addition, after the third rectifier switch (switch Q9) and the fourth rectifier switch (switch Q12) are turned off, and after the first modulation time MT, the modulation time calculation module TMC can output the first mode start signal, and The power converter circuit is periodically driven in the manner in the aforementioned first mode.

For the switches Q2, Q3, Q6, Q8, Q9, and Q12 corresponding to the second mode Φ2, the switches Q2, Q3, Q6, and Q8 other than the third rectifier switch (switch Q9) and the fourth rectifier switch (switch Q12) In other words, the second switch control circuit SW2 can be controlled by a fixed control method. The second switch control circuit SW2 can be configured to control the switches Q2, Q3, Q6, and Q8 to turn off the third rectifier switch (switch Q9) and the fourth rectifier switch (switch Q12) in response to receiving the first modulation time calculation signal. Turn off in the second modulation time MT2 after turning off.

In this embodiment, the modulation time calculation module TMC may include a first calculation unit CU1 and a second calculation unit CU2 to calculate the required modulation time in the first mode Φ1 and the second mode Φ2, respectively. Wherein, the first calculation unit CU1 is configured to calculate the first modulation time MT1 according to the feedback voltage when receiving the first modulation time calculation signal, and the first rectifier switch (switch Q11) and the second rectifier switch After the (switch Q7) is turned off, the second mode start signal is output after the first modulation time MT1 has elapsed.

Similarly, the second calculation unit CU2 is configured to, in response to receiving the second modulation time calculation signal, calculate the second modulation time MT2 according to the feedback voltage, and perform the operation between the third rectifier switch (switch Q9) and the fourth rectifier After the switch (switch Q12) is turned off, the first mode start signal is output after the second modulation time MT2.

[Second Embodiment]

Please further refer to FIG. 4, which is a functional block diagram of a control circuit for a power converter according to a second embodiment of the present invention. As shown in the figure, each unit of this embodiment is basically similar to that of FIG. 1, so part of the repeated description is omitted. The difference is that the modulation time calculation module TMC of this embodiment includes a third calculation unit CU3 and a phase shifter PS. The following is a description with reference to FIGS. 5 and 6 together. FIG. 5 is a circuit layout diagram of a power converter according to a second embodiment of the present invention, and FIG. 6 is a switching timing diagram according to a second embodiment of the present invention.

As shown in FIG. 5, the power converter may be a resonant switched capacitor converter (Resonant Switched Capacitor, ReSC), which includes a two-stage resonant tank arranged between an input terminal Vin and an output terminal Vout, and switches Q1' to Q8' and the output capacitor Cout and output resistance Rout connected to the output terminal Vout, wherein the switches Q1' to Q8' can respectively correspond to the first mode Φ1 and the second mode Φ2, and the input terminal Vin receives an input voltage. The first-level resonant tank may include a resonant capacitor C1 and a resonant inductor L01, the second-level resonant tank may include a resonant capacitor C2 and a resonant inductor L02, and the non-resonant capacitor Cm1 is a capacitor that is separated from the two-level resonant tank and does not contribute to the characteristic resonance frequency. . In this embodiment, only one non-resonant capacitor Cm1 is included in the circuit. However, depending on the topology of the ReSC circuit, more than one non-resonant capacitor may be used.

Among the switches Q1' to Q8', the switches Q2', Q3', Q6', and Q7' correspond to the first mode Φ1, and the switches Q1', Q4', Q5', and Q8' correspond to the second mode Φ2. In the mode Φ1 and the second mode Φ2, the off state or the on state of the switches Q1' to Q8' are mutually exclusive.

As shown in FIG. 6, the first mode Φ1 starts at time t0, and the first switch control circuit SW1 is configured to control the plurality of switches corresponding to the first mode Φ1 to turn on in the first mode Φ1. For example, the switches Q2', Q3', Q6', and Q7' are respectively controlled by the switch signals VGS2', VGS3', VGS6', and VGS7', and correspond to the switches Q1', Q4', Q5' of the second mode Φ2 , Q8' is controlled by switch signals VGS1', VGS4', VGS5', VGS8'. In this case, the first resonant current i1 along the first resonant path L1 and the second resonant current i2 along the second resonant path L2 can be respectively formed by the two-stage resonant tank.

The switches Q2', Q3', Q6', Q7' include a first rectifier switch located on the first resonance path L1, and a second rectifier switch located on the second resonance path L2. For example, it can be seen from the figure that the body diodes of the switches Q7' and Q3' follow the direction of the current, and therefore have a rectification function, which can be used as the aforementioned first rectifier switch and second rectifier switch, respectively.

Then, the first zero current detection circuit ZCD1 is configured to detect the first resonant current i2 on the first rectifier switch (the switch Q3' at this time), in other words, to detect the switch current ISD3' on the switch Q3' , When it is detected that the first resonant current i2 (that is, the switching current ISD3') reaches the current zero point, the first current zero point signal is output so that the first switch control circuit SW1 controls the first rectifier switch (switch Q3') to turn off, This is time t1.

At the same time, when the second resonant path L1 is generated, the second zero current detection circuit ZCD2 is also configured to detect the second resonant current i1 on the second rectifier switch (in this case, the switch Q7'), in other words, The switch current ISD7' on the switch Q7' is detected. When it is detected that the second resonant current i1 reaches the current zero point, the second current zero point signal is output so that the first switch control circuit SW1 controls the second rectifier switch (switch Q7' ) Turn off, this time is time t2.

Further, the first switch off detector OFFC1 is configured to detect whether the first rectifier switch and the second rectifier switch are both off. At time t2, when it is detected that both the first rectifier switch (switch Q7') and the second rectifier switch (switch Q3') are turned off, the first modulation time calculation signal is output.

As shown in FIG. 4, the third calculation unit CU3 is respectively connected to the first switch control circuit SW1, the feedback circuit FB, the first switch off detector OFFC1 and the second switch off detector OFFC2, and the phase shifter PS is connected between the third calculation unit CU3 and the second switch control circuit SW2.

The third calculation unit CU3 can be used to receive the first modulation time calculation signal and the second modulation time calculation signal. In response to receiving the first modulation time calculation signal or the second modulation time calculation signal, the third calculation unit CU3 is configured to calculate the total modulation time TMT according to the feedback voltage, and correspondingly generate a time modulation signal.

Further, the phase shifter PS is configured to, in response to receiving the modulation time signal, phase-shift the modulation time signal according to one-half of the total modulation time TMT, for example, the phase shift amount Phase as shown in the figure A post-phase shift modulated time signal is generated, and the modulated time signal and the post-phase shifted modulated time signal are respectively output as the second mode activation signal and the first mode activation signal.

In other words, unlike the previous embodiment, the start time of the second mode Φ2 is essentially controlled by the phase shifter PS, that is, the switching cycle time of the first mode Φ1 (that is, the first mode activation signal) is phased Shifted by 180 degrees, therefore, at time t3, the switches Q1', Q4', Q5', and Q8' corresponding to the second mode Φ2 can be triggered by outputting the second mode activation signal.

In the second mode Φ2, the second switch control circuit SW2 is configured to control the switches Q1', Q4', Q5', and Q8' corresponding to the second mode Φ2 to be turned on in response to receiving the second mode activation signal. A third resonant current i3 along the third resonant path L3 and a fourth resonant current i4 along the fourth resonant path L4 are respectively formed through the resonant slot. Similarly, the switches Q1', Q4', Q5', and Q8' include a third rectifier switch (in this case, switch Q1') located on the third resonant path L3 and a fourth rectifier located on the fourth resonant path L4 Switch (in this case, switch Q5').

Then, the third zero current detection circuit ZCD3 is configured to detect the third resonant current i3 on the third rectifier switch (switch Q1'), in other words, to detect the switch current ISD1' on the switch Q1', when the detection When the third resonant current (that is, the switch current ISD1') reaches the current zero point, the third current zero point signal is output so that the second switch control circuit SW2 controls the third rectifier switch (switch Q1') to turn off. This time is the time t4.

At the same time, when the fourth resonant path L4 is generated, the fourth zero current detection circuit ZCD4 is configured to detect the fourth resonant current i4 (that is, the switch current ISD5') on the fourth rectifier switch (switch Q5') , When it is detected that the fourth resonant current i4 (switch current ISD5') reaches the current zero point, the fourth current zero point signal is output so that the second switch control circuit SW2 controls the fourth rectifier switch (switch Q5') to turn off. Time t5.

The second switch off detector OFFC2 is configured to detect whether the third rectifier switch and the fourth rectifier switch are both off. And when the third rectifier switch and the fourth rectifier switch are both turned off, a second modulation time calculation signal is output. Wherein, at time t5, when it is detected that both the third rectifier switch (switch Q1') and the fourth rectifier switch (switch Q5';) are turned off, the first modulation time calculation signal is output.

Then, the third calculation unit CU3 is further configured to, in response to receiving the second modulation time calculation signal, calculate the total modulation time TMT used in the next cycle according to the feedback voltage from the output terminal Vout, and generate the next cycle at the same time The first mode activation signal and the second mode activation signal are used.

[Beneficial effects of the embodiment]

One of the beneficial effects of the present invention is that the control circuit and control method for a power converter provided by the present invention can enable the rectifier switch of a power converter with multiple sets of rectification paths through a zero current detection circuit. Determine the on-time individually. Not only can it overcome the different conduction time of the rectifier switch caused by the component error of the individual rectifier loop, but also can achieve the function of zero voltage turn-on and zero current cut-off of the rectifier component, so as to optimize the overall efficiency of the power converter.

In addition, after ensuring that all rectification paths of the power converter have completed zero current cutoff, adjust the trigger timing of the switching signal of the power converter to achieve the modulation of the converter output impedance, achieve the output adjustable voltage, and the parallel output can share the current function. .

The content disclosed above is only the preferred and feasible embodiments of the present invention, and does not limit the scope of the patent application of the present invention. Therefore, all equivalent technical changes made using the description and schematic content of the present invention are included in the application of the present invention. Within the scope of the patent.

Vin: input Vout: output RS1, RS2: Resonant tank Q1~Q12, Q1’ ~Q8’: switch Φ1: The first mode Φ2: The second mode CR1, CR2, C1, C2: resonant capacitor LR1, LR2, L01, L02: resonant inductor CF1, Cm1: Non-resonant capacitor 1: Control circuit SW1: The first switch control circuit ZCD1: The first zero current detection circuit ZCD2: The second zero current detection circuit OFFC1: The first switch turns off the detector TMC: Modulation time calculation module SW2: The second switch control circuit ZCD3: The third zero current detection circuit ZCD4: The fourth zero current detection circuit OFFC2: The second switch turns off the detector t, t0, t1, t2, t3, t4, t5, t6: time VGS1~VGS12, VGS1’ ~VGS8’: switch signal L1: first resonance path i1: first resonant current L2: second resonance path i2: second resonant current L3: Third resonance path i3: third resonant current L4: Fourth resonance path i4: fourth resonance current ISD7, ISD9, ISD11, ISD12, ISD3’, ISD7’, ISD1’, ISD5’: Switching current MT1: first modulation time MT2: Second modulation time FB: feedback circuit CU1: the first computing unit CU2: The second computing unit CU3: The third computing unit PS: Phase shifter Phase: The amount of phase shift Cout: output capacitance Rout: output resistance TMT: total modulation time

Fig. 1 is a functional block diagram of a control circuit for a power converter according to a first embodiment of the present invention.

Fig. 2 is a circuit layout diagram of the power converter according to the first embodiment of the present invention.

Fig. 3 is a switch timing diagram according to the first embodiment of the present invention.

Fig. 4 is a functional block diagram of a control circuit for a power converter according to a second embodiment of the present invention.

Fig. 5 is a circuit layout diagram of a power converter according to a second embodiment of the present invention.

Fig. 6 is a switch timing diagram according to the second embodiment of the present invention.

1: Control circuit

SW1: The first switch control circuit

SW2: The second switch control circuit

ZCD1: The first zero current detection circuit

ZCD2: The second zero current detection circuit

TMC: Modulation time calculation module

ZCD3: The third zero current detection circuit

ZCD4: The fourth zero current detection circuit

OFFC1: The first switch turns off the detector

OFFC2: The second switch turns off the detector

FB: feedback circuit

CU1: the first computing unit

CU2: The second computing unit

Claims (10)

A control method for a power converter, wherein the power converter includes a plurality of resonance tanks and a plurality of switches arranged between an input terminal and an output terminal, wherein the open relations correspond to a first mode and A second mode, and the input terminal receives an input voltage, the control method includes: Configure a first switch control circuit in the first mode to control the conduction of a plurality of switches corresponding to the first mode, so as to form a first resonant current along a first resonant path and a first resonant current along a first resonant path through the resonant slots. A second resonant current of a second resonant path, wherein the switches include a first rectifier switch located on the first resonant path and a second rectifier switch located on the second resonant path; A first zero current detection circuit is configured to detect the first resonant current on the first rectifier switch, and when it is detected that the first resonant current reaches the current zero point, a first current zero point signal is output to enable the first switch The control circuit controls the first rectifier switch to turn off; A second zero current detection circuit is configured to detect the second resonant current on the second rectifier switch, and when it is detected that the second resonant current reaches the current zero point, a second current zero point signal is output to enable the first switch The control circuit controls the second rectifier switch to turn off; A first switch turn-off detector is configured to detect whether the first rectifier switch and the second rectifier switch are both turned off, and when the first rectifier switch and the second rectifier switch are both turned off, output a first Modulation time calculation signal; A modulation time calculation module is configured, in response to receiving the first modulation time calculation signal, a first modulation time is calculated according to a feedback voltage from the output terminal, and the first rectification switch and the second After the rectifier switch is turned off, a second mode start signal is output after the first modulation time has elapsed; A second switch control circuit is configured, and in response to receiving the second mode activation signal, the switches corresponding to the second mode are controlled to be turned on, so as to form a third resonant path along a third resonance path through the resonant tanks. Resonant current and a fourth resonant current along a fourth resonant path, where the switches include a third rectifier switch located on the third resonant path and a fourth rectifier located on the fourth resonant path switch; A third zero current detection circuit is configured to detect the third resonant current on the third rectifier switch, and when it is detected that the third resonant current reaches the current zero point, a third current zero point signal is output to enable the second switch The control circuit controls the first rectifier switch to turn off; A fourth zero current detection circuit is configured to detect the fourth resonant current on the fourth rectifier switch, and when it is detected that the second resonant current reaches the current zero point, a fourth current zero point signal is output to enable the second switch The control circuit controls the fourth rectifier switch to turn off; A second switch turn-off detector is configured to detect whether the third rectifier switch and the fourth rectifier switch are both turned off, and when the third rectifier switch and the fourth rectifier switch are both turned off, output a second Modulation time calculation signal; Configure the modulation time calculation module, in response to receiving the second modulation time calculation signal, calculate a second modulation time according to the feedback voltage, and turn off the third rectifier switch and the fourth rectifier switch Then, after the second modulation time has elapsed, a first mode activation signal is output. The control method for the power converter as described in claim 1, further includes: The first switch control circuit is configured to control the switches corresponding to the first mode in response to receiving the first modulation time calculation signal. The switches other than the first rectifier switch and the second rectifier switch are in The first rectifier switch and the second rectifier switch are turned off within the first modulation time after the second rectifier switch is turned off. The control method for the power converter as described in claim 1, further includes: Configure the second switch control circuit, in response to receiving the second modulation time calculation signal, control the switches corresponding to the second mode, the third rectifier switch and the fourth rectifier switch other than the switches The third rectifier switch and the fourth rectifier switch are turned off within the second modulation time after they are turned off. The control method for a power converter according to claim 1, wherein the modulation time calculation module includes a first calculation unit and a second calculation unit, and the control method further includes: The first calculation unit is configured to, in response to receiving the first modulation time calculation signal, calculate the first modulation time according to the feedback voltage, and after the first rectifier switch and the second rectifier switch are turned off , Output the second mode activation signal after the modulation time has elapsed; The second calculation unit is configured to, in response to receiving the second modulation time calculation signal, calculate the second modulation time according to the feedback voltage, and after the third rectifier switch and the fourth rectifier switch are turned off , And output the first mode activation signal after the second modulation time has elapsed. The control method for a power converter according to claim 1, wherein the modulation time calculation module includes a third calculation unit and a phase shifter, and the control method further includes: The third calculation unit is configured to, in response to receiving the first modulation time calculation signal or the second modulation time calculation signal, calculate a total modulation time according to the feedback voltage, and correspondingly generate a time modulation signal ;as well as Configure the phase shifter, in response to receiving the modulation time signal, phase-shift the modulation time signal according to one-half of the total modulation time to generate a phase-shifted modulation time signal, and use the The modulation time signal and the phase-shifted modulation time signal are output as the second mode activation signal and the first mode activation signal. A control circuit for a power converter, wherein the power converter includes a plurality of resonance tanks and a plurality of switches arranged between an input terminal and an output terminal, wherein the open relations correspond to a first mode and A second mode, and the input terminal receives an input voltage, the control circuit includes: A first switch control circuit configured to control the conduction of a plurality of switches corresponding to the first mode in the first mode, so as to respectively form a first resonance current along a first resonance path through the resonance tanks And a second resonant current along a second resonant path, wherein the switches include a first rectifier switch located on the first resonant path and a second rectifier switch located on the second resonant path; A first zero current detection circuit, configured to detect the first resonant current on the first rectifier switch, and output a first current zero signal when detecting that the first resonant current reaches the current zero point to enable the The first switch control circuit controls the first rectifier switch to turn off; A second zero current detection circuit is configured to detect the second resonant current on the second rectifier switch, and output a second current zero signal when detecting that the second resonant current reaches the current zero point to enable the The first switch control circuit controls the second rectifier switch to turn off; A first switch turn-off detector configured to detect whether the first rectifier switch and the second rectifier switch are both turned off, and output when the first rectifier switch and the second rectifier switch are both turned off A first modulation time calculation signal; A modulation time calculation module is configured to, in response to receiving the first modulation time calculation signal, calculate a first modulation time based on a feedback voltage from the output terminal, and set the signal between the first rectifier switch and the After the second rectifier switch is turned off, a second mode start signal is output after the first modulation time has elapsed; A second switch control circuit is configured to control the switches corresponding to the second mode to be turned on in response to receiving the second mode activation signal, so as to form a third resonance path along a third resonance path through the resonant tanks. The third resonant current and a fourth resonant current along a fourth resonant path, wherein the switches include a third rectifier switch located on the third resonant path and a first resonant switch located on the fourth resonant path Four rectifier switch; A third zero current detection circuit, configured to detect the third resonant current on the third rectifier switch, and output a third current zero signal when detecting that the third resonant current reaches the current zero point to make the The second switch control circuit controls the first rectifier switch to turn off; A fourth zero current detection circuit, configured to detect the fourth resonant current on the fourth rectifier switch, and output a fourth current zero signal when detecting that the second resonant current reaches the current zero point to enable the The second switch control circuit controls the fourth rectifier switch to turn off; A second switch turn-off detector configured to detect whether the third rectifier switch and the fourth rectifier switch are both turned off, and output when the third rectifier switch and the fourth rectifier switch are both turned off 1. The second modulation time calculation signal; The modulation time calculation module is further configured to, in response to receiving the second modulation time calculation signal, calculate a second modulation time according to the feedback voltage, and perform the operation between the third rectifier switch and the fourth rectifier After the switch is turned off, and after the second modulation time has elapsed, a first mode activation signal is output. The control circuit for a power converter according to claim 6, wherein the first switch control circuit is further configured to control the switches corresponding to the first mode in response to receiving the first modulation time calculation signal Wherein, the switches other than the first rectifier switch and the second rectifier switch are turned off within the first modulation time after the first rectifier switch and the second rectifier switch are turned off. The control circuit for a power converter according to claim 6, wherein the second switch control circuit is further configured to control the switches corresponding to the second mode in response to receiving the second modulation time calculation signal Wherein, the switches other than the third rectifier switch and the fourth rectifier switch are turned off during the second modulation time after the third rectifier switch and the fourth rectifier switch are turned off. The control circuit for a power converter according to claim 6, wherein the modulation time calculation module includes a first calculation unit and a second calculation unit, and the first calculation unit is configured to respond to receiving When the signal is calculated for the first modulation time, the first modulation time is calculated according to the feedback voltage, and after the first rectifier switch and the second rectifier switch are turned off, the second rectifier switch is output after the modulation time has elapsed. Mode start signal, The second calculation unit is configured to, in response to receiving the second modulation time calculation signal, calculate the second modulation time according to the feedback voltage, and turn off the third rectifier switch and the fourth rectifier switch Then, after the second modulation time has elapsed, the first mode activation signal is output. The control circuit for a power converter according to claim 6, wherein the modulation time calculation module includes a third calculation unit and a phase shifter, and the third calculation unit is configured to respond to receiving the When the first modulation time calculation signal or the second modulation time calculation signal, a total modulation time is calculated according to the feedback voltage, and a time modulation signal is generated correspondingly, The phase shifter is configured to, in response to receiving the modulation time signal, phase-shift the modulation time signal according to one-half of the total modulation time to generate a phase-shifted modulation time signal, and respectively The modulation time signal and the phase-shifted modulation time signal are output as the second mode activation signal and the first mode activation signal.

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